1. Field of the Invention
The invention relates to a buttonhole sewing machine for producing in a work piece buttonhole seams with seam end sections of various shapes.
2. Background Art
In clothes such as coats, jackets, shirts etc. which are closed at the front by buttons and buttonholes, the menswear buttonholes are disposed in mirror-image arrangement as compared to ladies"" wear buttonholes. In these buttonholes, the thread supplied by the needle to the sewing machine extends approximately in the form of a line on the externally visible side where the button comes to rest after buttoning.
In some clothes, for example in knitwear, the buttonholes run lengthwise in parallel to the edge of the work piece. The buttonholes are disposed one after the other in the longitudinal direction. They have seam end sections of varying shape i.e., stay stitching of various shapes such as round stays, wedge-shaped stays, zigzag stays or eye-type stays.
For buttonhole seams of this type to be sewn, U.S. Pat. No. 3,216,381 describes a buttonhole sewing machine of the generic type, comprising a base plate, a top arm and a standard that unites the base plate and the arm, and a needle bar which is lodged in the arm and provided with a needle and which reciprocates up and down, drivable substantially in a z direction by means of a main driving motor. Furthermore, this sewing machine comprises a work piece clamp which is displaceable in the y direction i.e., in the longitudinal direction of the machine, clamping the work piece. The standard stands back from a y-z plane that passes through the needle. This design enables a work piece to be placed with its buttonhole edge in parallel to the longitudinal direction of the arm i.e., in the longitudinal direction of the sewing machine, without being obstructed by the standard. Producing the buttonhole seams, mentioned at the outset, of mirror-image design depending on whether they are intended for ladies"" wear or menswear will require a specific sewing machine in each case.
It is an object of the invention to embody a buttonhole sewing machine of the generic type in such a way that it can easily be reconverted, enabling mirror-inverted production of buttonholes of varying end sections.
According to the invention, this object is attained in a buttonhole sewing machine for producing buttonhole seams with seam end sections of various shapes in a work piece, comprising a base plate, a top arm and a standard that unites the base plate and the arm; a needle bar, which is housed in the arm and provided with a needle and which reciprocates up and down, drivable by a main driving motor substantially in a z direction; a table which is displaceable by a y driving motor in a y direction; a work piece clamp, which is disposed on the table, clamping the work piece on the table; a driving motor for producing a motion, in an x direction, of the needle relative to the work piece; a control system for controlling the driving motors, which an input equipment for buttonhole-parameter input is allocated to, which comprises a computer for computation, from the buttonhole parameters, of sewing data that determine a respective buttonhole geometry, which comprises a memory for storage of the computed sewing data, and which comprises a key to be shifted into two key statuses and by which to trigger conversion of the sewing data of a buttonhole seam from a position to the left into a position to the right or vice versa, and storage thereof. The buttonhole sewing machine according to the invention is embodied such that mirror-imaged or mirror-inverted buttonholes can be produced without any complicated program-input requirements. Placing the work piece in one direction or the other, as for example lapels to the left or to the right, enables the sewing data i.e., stitching coordinates, to be converted rather flexibly at the touch of a button as it were, The control system causes the driving motors and control units to be correspondingly triggered. Based on the measures according to the invention, the parameters that have been stored for a buttonhole can be used for a mirror-inverted buttonhole. Online calculation of the stitching coordinates takes place for the desired buttonhole. An available memory can be used for varying programs. Program conversion takes place rapidly and easily. Machine standstill is reduced. Simplicity of operation facilitates work. High operational reliability is accomplished because errors due to maloperation and faulty programming are strongly reduced.
Details of the invention will become apparent from the ensuing description of an exemplary embodiment, taken in conjunction with the drawing.